J/A+A/330/881 Radial velocities of Cartwheel Galaxy (Amram+ 1998)
The Hα kinematics of the Cartwheel galaxy
Amram P., Mendes de Oliveira C., Boulesteix J., Balkowski C.
<Astron. Astrophys. 330, 881 (1998)>
=1998A&A...330..881A 1998A&A...330..881A (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, ring ; Radial velocities
Keywords: galaxies: interactions - galaxies: ISM -
galaxies: kinematics and dynamics - galaxies: individual (Cartwheel) -
galaxies: structure
Abstract:
We report on high spectral and spatial resolution kinematic
observations of Hα emission from the Cartwheel system obtained
with a scanning Fabry-Perot interferometer. Velocity fields for two
galaxies were measured, for the main galaxy of the system, the
Cartwheel galaxy, and for a spiral companion ∼25h-1kpc to the
north. The velocity field and the rotation curve of the spiral
companion shows classical differential rotation and indicates the mass
of the galaxy to be in the range 2.9-4.8x109M☉. The Cartwheel
galaxy contains strong Hα in emission asymmetrically distributed
along its outer ring, with some faint emission detected inside it. The
velocity field and the rotation curve of the Cartwheel galaxy is
clearly dominated by differential rotation although second-order
effects cause distortions which can be understood in a scenario where
expansion and density-wave motions are also considered. Our best
model-fit to the observed velocity field of the Cartwheel galaxy
includes three components for the kinematic of its outer ring: a
circular velocity of 217km/s, an expansion velocity of 13-30±10km/s
and a sinusoidal perturbation with an amplitude of 20±5km/s. This
expansion velocity, lower than found in previous studies, implies that
the ring could be older than previously thought. The rotation curve of
the Cartwheel galaxy is consistent with a progenitor which had the
morphology of a late-type spiral galaxy. Our measurements support the
collisional models of ring galaxy formation and should impose strong
constraints to simulations.
Objects:
----------------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------------
00 37 40.7 -33 42 58 Cartwheel galaxy = ESO 350- 40
----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3a 39 21 Radial characteristics of the Cartwheel (Fig. 5)
table3b 39 25 Radial characteristics for the spiral companion
(Fig. 11)
table3.tex 106 96 LaTeX version of the tables
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3a table3b
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 F4.1 arcsec Rad Mean radius of the annulus on the major axis
6- 7 I2 --- Napp Number of points with measurable radial velocities
in this annulus for the approaching side
9- 11 I3 km/s Vapp ? Weighted average velocity calculated from Napp
velocity points
13- 14 I2 km/s e_Vapp ? rms uncertainty on Vapp
16- 18 I3 --- Nrec Number of points with measurable radial velocities
in this annulus for the receding side
20- 22 I3 km/s Vrec ? Weighted average velocity calculated from Nrec
velocity points
24- 26 I3 km/s e_Vrec ? rms uncertainty on Vrec
28- 30 I3 --- Ntot Total number of velocity points in the annulus
Napp+Nrec
33- 35 I3 km/s Vel Weighted average velocity calculated from
both sides
37- 39 I3 km/s e_Vel rms uncertainty on Vel
--------------------------------------------------------------------------------
Acknowledgements: Philippe Amram
(End) Patricia Bauer [CDS] 20-Aug-1997